Generally, in a commercial electrostatographic reproduction apparatus (such as copier/duplicators, printers, or the like), a latent image charge pattern is formed on a uniformly charged photoconductive or dielectric member. Pigmented marking particles (toner) are attracted to the latent image charge pattern to develop such image on the dielectric member. A receiver member, such as paper, is then brought into contact with the dielectric member and an electric field applied to transfer the marking particle developed image to the receiver member from the dielectric member. After transfer, the receiver member bearing the transferred image is transported away from the dielectric member and the image is fixed or fused to the receiver member by heat and/or pressure to form a permanent reproduction thereon. In a typical fusing process where the toner is fused to the paper or receiving member, two rolls are used through which the paper travels during the toner fusing. One roll, usually the harder roll, is a fuser roll, the second roll is the pressure roll or the softer roll.
Typical pressure rolls (“Softer Roll”) that are used in a fusing system have an elastomeric coating like silicone which may or may not have a thin layer of another material over the surface of the roll. A functional nip is formed when the softer roll is pressed into the fuser roll (“Harder Roll”). If the softer roll is shorter than the harder roll, a support plate at the end of the roll is needed to help contain the pressure roll elastomer (silicone) material as it is pushed out during the transition through the nip. The action of the elastomer rubbing on the support plate causes the elastomer to wear and create debris in the system and excessive wear on the roll.
The pressure rolls or softer rolls are typically constructed of a cylindrical steel core or rod having positioned over it an elastomer material cylindrical roll. At the ends of the elastomer roll, generally, are positioned endplates or steel washers. In any system when a hard roll is pressed against and contacts a softer roll, high pressure zones are formed at the ends of the softer roll. These pressure zones ultimately cause the softer material to contact the support plates and create wear, shortening roll life and causing debris in the system. Also, once excessive wear takes place, improper fusing of the toner can result causing imperfect copies on the paper or receiving member. In addition, because of this wear problem, frequent changes requiring new softer rolls are required. Generally, the elastomeric rolls have typically been manufactured from a single elastomeric material such as silicon rubber, of a uniform hardness as determined by a durometer. From both a cost standpoint and performance standpoint, any improvement in the softer roll construction that would extend roll life and improve performance at the fuser station would be very desirable. Thus, eliminating material deterioration of the pressure roll would extend pressure roll life and improve fusing performance.